158 lines
3.6 KiB
Plaintext
158 lines
3.6 KiB
Plaintext
.TH SCRIBBLE 2
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.SH NAME
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scribblealloc,
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recognize \- character recognition
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.SH SYNOPSIS
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.PP
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.EX
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.ta 4n +4n +4n +4n +4n +4n +4n +4n +4n +4n
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#include <u.h>
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#include <libc.h>
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#include <draw.h>
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#include <scribble.h>
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Scribble *scribblealloc(void);
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Rune recognize(Scribble *);
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.EE
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.SH DESCRIPTION
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.PP
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The scribble library implements simple character recognition.
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All characters are drawn using a single stroke of the pen (mouse button 1)
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as on a palmtop computer.
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.PP
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The library is not really intended for standalone use. Its primary
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use is by the scribble graphical control (see
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.IR control (2)).
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.PP
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.B Scribblealloc
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allocates and returns an appropriately initialized
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.B Scribble
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structure:
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.IP
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.EX
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.ta 4n +4n +4n +4n +4n +4n +4n +4n +4n +4n
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#define CS_LETTERS 0
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#define CS_DIGITS 1
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#define CS_PUNCTUATION 2
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struct Scribble {
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/* private state */
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Point *pt;
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int ppasize;
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Stroke ps;
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Graffiti *graf;
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int capsLock;
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int puncShift;
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int tmpShift;
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int ctrlShift;
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int curCharSet;
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};
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.EE
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.PP
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This structure encodes the points making up the stroke
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to be recognized, as well as the \f2character group\fP in which
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the stroke should be searched.
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.PP
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There are three such groups:
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.IR letters ,
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.IR digits ,
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and
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.IR punctuation .
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The current group is encoded in the
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.B curCharSet
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field of the
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.B Scribble
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structure.
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Special strokes are recognized to switch between groups.
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In addition, the charater recognized is influenced by
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.I mode
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parameters and modifies them.
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These are identified by the
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.BR capsLock ,
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.BR puncShift ,
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.BR tmpShift ,
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and
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.B ctrlShift
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fields of the
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.B Scribble
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structure.
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When
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.B puncShift
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is non-zero, the character is recognized in the punctuation
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character set.
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Similarly,
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when the character recognized is printable and
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.B ctrlShift
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is set, the associated control character is returned as if the
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control key were depressed,
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and when the character is a letter and
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.B capsLock
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or
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.B tmpShift
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is set, the upper-case version is returned.
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The
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.B puncShift
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and
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.B tmpShift
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flags are turned off
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once a character has been recognized; the others are left set.
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.PP
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The character to be recognized is encoded as an array of pen_points in the
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.B ps
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field.
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To allow easy drawing of the stroke as it is drawn,
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the
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.I pt
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and
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.I ppasize
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fields are available to the application code for storing an array
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of points for a call to
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.B poly
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(see
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.IR draw (2)).
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.PP
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.I Recognize
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recognizes the character provided in the
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.B ps
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field of the
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.B Scribble
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structure; it
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returns the rune or zero if nothing was recognized.
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.SH FILES
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.B /sys/lib/scribble/classifiers
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contains the stroke definitions.
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.SH SOURCE
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.B /sys/src/libscribble
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.PP
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This library is adapted from software reproduced by permission:
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.PP
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.B Graffiti.c
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is based on the file
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.B Scribble.c
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copyrighted
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by Keith Packard:
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.IP
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Copyright © 1999 Keith Packard
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.PP
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Permission to use, copy, modify, distribute, and sell this software and its
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documentation for any purpose is hereby granted without fee, provided that
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the above copyright notice appear in all copies and that both that
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copyright notice and this permission notice appear in supporting
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documentation, and that the name of Keith Packard not be used in
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advertising or publicity pertaining to distribution of the software without
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specific, written prior permission. Keith Packard makes no
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representations about the suitability of this software for any purpose. It
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is provided "as is" without express or implied warranty.
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.PP
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Portions of the software Copyright © 1994 by Sun Microsystems Computer Company.
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.PP
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Portions of the software Copyright © 2000 by Compaq Computer Corporation.
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.SH SEE ALSO
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.B Keyboard
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and
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.B prompter
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in
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.IR bitsyload (1),
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.IR draw (2),
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.IR control (2)
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